#
# Copyright 2020 The XLS Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Memoization decorator helper."""

import functools

_SENTINEL = object()


def memoize(f):
  """Returns a version of the given callable that has memoized results."""
  cache = {}

  @functools.wraps(f)
  def memoizing_wrapper(*args):
    result = cache.get(args, _SENTINEL)
    if result is _SENTINEL:
      result = cache[args] = f(*args)
    return result

  return memoizing_wrapper
